In recent years all-purpose liquid detergents have become widely accepted for cleaning hard surfaces, e.g., painted woodwork and panels, tiled walls, wash bowls, bathtubs, linoleum or tile floors, washable wall paper, etc. Such all-purpose liquids comprise clear and opaque aqueous mixtures of water-soluble synthetic organic detergents and water-soluble detergent builder salts. In order to achieve comparable cleaning efficiency with granular or powdered all-purpose cleaning compositions, use of water-soluble inorganic phosphate builder salts was favored in the prior art all-purpose liquids. For example, such early phosphate-containing compositions are described in U.S. Pat. Nos. 2,560,839; 3,234,138; 3,350,319; and British Patent No. 1,223,739.
In view of the environmentalist's efforts to reduce phosphate levels in ground water, improved all-purpose liquids containing reduced concentrations of inorganic phosphate builder salts or non-phosphate builder salts have appeared. A particularly useful self-opacified liquid of the latter type is described in U.S. Pat. No. 4,244,840.
However, these prior art all-purpose liquid detergents containing detergent builder salts or other equivalent tend to leave films, spots or streaks on cleaned unrinsed surfaces, particularly shiny surfaces. Thus, such liquids require thorough rinsing of the cleaned surfaces which is a time-consuming chore for the user.
In order to overcome the foregoing disadvantage of the prior art all-purpose liquid, U.S. Pat. No. 4,017,409 teaches that a mixture of paraffin sulfonate and a reduced concentration of inorganic phosphate builder salt should be employed. However, such compositions are not completely acceptable from an environmental point of view based upon the phosphate content. On the other hand, another alternative to achieving phosphate-free all-purpose liquids has been to use a major proportion of a mixture of anionic and nonionic detergents with minor amounts of glycol ether solvent and organic amine as shown in U.S. Pat. No. 3,935,130. Again, this approach has not been completely satisfactory and the high levels of organic detergents necessary to achieve cleaning cause foaming which, in turn, leads to the need for thorough rinsing which has been found to be undesirable to today's consumers.
Another approach to formulating hard surface or all-purpose liquid detergent composition where product homogeneity and clarity are important considerations involves the formation of oil-in-water (o/w) microemulsions which contain one or more surface-active detergent compounds, a water-immiscible solvent (typically a hydrocarbon solvent), water and a "cosurfactant" compound which provides product stability. By definition, an o/w microemulsion is a spontaneously forming colloidal dispersion of "oil" phase particles having a particle size in the range of 25 to 800 .ANG. in a continuous aqueous phase. In view of the extremely fine particle size of the dispersed oil phase particles, microemulsions are transparent to light and are clear and usually highly stable against phase separation.
Patent disclosures relating to use of grease-removal solvents in o/w microemulsions include, for example, European Patent Applications EP 013761 5and EP 0137616--Herbots et al; European Patent Application EP 0160762--Johnston et al; and U.S. Pat. No. 4,561,991--Herbots et al. Each of these patent disclosures also teaches using at least 5% by weight of grease-removal solvent.
It also is known from British Patent Application GB 2144763A to Herbots et al, published Mar. 13, 1985, that magnesium salts enhance grease-removal performance of organic grease-removal solvents, such as the terpenes, in o/w microemulsion liquid detergent compositions. The compositions of this invention described by Herbots et al. require at least 5% of the mixture of grease-removal solvent and magnesium salt and preferably at least 5% of solvent (which may be a mixture of water-immiscible non-polar solvent with a sparingly soluble slightly polar solvent) and at least 0.1% magnesium salt.
However, since the amount of water immiscible and sparingly soluble components which can be present in an o/w microemulsion, with low total active ingredients without impairing the stability of the microemulsion is rather limited (for example, up to 18% by weight of the aqueous phase), the presence of such high quantities of grease-removal solvent tend to reduce the total amount of greasy or oily soils which can be taken up by and into the microemulsion without causing phase separation. The following representative prior art patents also relate to liquid detergent cleaning compositions in the form of o/w microemulsions: U.S. Pat. Nos. 4,472,291--Rosario; 4,540,448-Gauteer et al; 3,723,33--Sheflin; etc.
Liquid detergent compositions which include terpenes, such as d-limonene, or other grease-removal solvent, although not disclosed to be in the form of o/w microemulsions, are the subject matter of the following representative patent documents: European Patent Application 0080749; British Patent Specification 1,603,047; 4,414,128; and 4,540,505. For example, U.S. Pat. No. 4,414,128 broadly discloses an aqueous liquid detergent composition characterized by, by weight:
(a) from 1% to 20% of a synthetic anionic, nonionic, amphoteric or zwitterionic surfactant or mixture thereof; PA1 (b) from 0.5% to 10% of a mono- or sesquiterpene or mixture thereof, at a weight ratio of (a):(b) being in the range of 5:1 to 1:3; and PA1 (c) from 0.5% 10% of a polar solvent having a solubility in water at 15.degree. C. in the range of from 0.2% to 10%. Other ingredients present in the formulations disclosed in this patent include from 0.05% to 2% by weight of an alkali metal, ammonium or alkanolammonium soap of a C.sub.13 -C.sub.24 fatty acid; a calcium sequestrant from 0.5% to 13% by weight; non-aqueous solvent, e.g., alcohols and glycol ethers, up to 10% by weight; and hydrotropes, e.g., urea, ethanolamines, salts of lower alkylaryl sulfonates, up to 10% by weight. All of the formulations shown in the Examples of this patent include relatively large amounts of detergent builder salts which are detrimental to surface shine. PA1 from 1.0% to 20% by weight of an anionic surfactant; PA1 from 3.0% to 10% by weight of a nonionic surfactant PA1 from 0.1% to 50% of a water-mixable cosurfactant having either limited ability or substantially no ability to dissolve oily or greasy soil; PA1 from 0.1% to 10% of a grease release agent, which is a polyethylene glycol or polyvinyl pyrrolidone either of which is complexed with said anionic surfactant; PA1 0 to 15% of magnesium sulfate heptahydrate; PA1 0.4 to 10.0% of a perfume or water insoluble hydrocarbon; and PA1 the balance being water, said proportions being based upon the total weight of the composition, wherein the concentration of the anionic surfactant always exceeds the concentration of the nonionic surfactant in the composition and the composition does not contain any anionic polymer, cationic polymer, octanol, cationic disinfectant and/or benzalkonium chloride. PA1 (a) 4 to 50 wt. % of at least two surfactant, wherein one of the surfactants is an anionic surfactant and the other surfactant is selected from the group consisting of nonionic surfactants, zwitterionic surfactants and alkyl polysaccharides surfactants and mixtures thereof, wherein the concentration of the anionic surfactant always exceeds the concentration of the other surfactant in the composition; PA1 (b) 0.1 to 10 wt. % of a grease release agent, which is a polyethylene glycol or polyvinyl pyrrolidone either of which is complexed with said anionic surfactant; PA1 (c) 0 to 15 wt. % of a solubilizing agent; and PA1 (d) the balance being water. PA1 (a) 1 to 30% of an anionic surfactant; PA1 (b) 1 to 15% of a cosurfactant; PA1 (c) 0.1 to 5% of a magnesium containing inorganic compound; PA1 (d) 0.05 to 0.3% of a perfume; PA1 (e) 0.1 to 10% of a grease release agent which is a polyethylene glycol which is complexed with said anionic surfactant; and PA1 (f) the balance being water, wherein the composition does not contain nonionic surfactant. PA1 (a) 1 to 30% of an anionic surfactant; PA1 (b) 0.1 % to 10% of a grease release agent which is a polyethylene glycol or a polyvinyl pyrrolidone either of which is complexed with the anionic surfactant; PA1 (c) 0.1 to 50% of a cosurfactant; PA1 (d) 0.4 to 10% of a water insoluble hydrocarbon or perfume; PA1 (e) 0 to 18% of at least one dicarboxylic acid; PA1 (f) 0 to 1% of phosphoric acid; PA1 (g) 0 to 0.2% of an aminoalkylene phosphonic acid; PA1 (h) 0 to 15% of magnesium sulfate heptahydrate; and PA1 (i) the balance being water, wherein the composition preferably does not contain any nonionic surfactant. PA1 (a) 4 to 50 wt. %, more preferably 2 to 40 wt. % and most preferably 3 to 35 wt. % of at least two surfactant one of said surfactants being an anionic surfactant and the other surfactant being selected from the group consisting of nonionic surfactants, zwitterionic surfactants, and alkyl polysaccharide surfactants, wherein the concentration of the anionic surfactant always exceeds the concentration of the other surfactant in the composition; PA1 (b) 0.1 to 10 wt. %, more preferably 0.4 to 8 wt. % of a grease release agent which is a polyethylene glycol polyvinyl pyrrolidone either of which is complexed with the anionic surfactant; PA1 (c) 0 to 15 wt. %, more preferably 1 to 12 wt. % of a solubilizing agent; and PA1 (d) the balance being water. PA1 R.sub.2 =CH.sub.3, CH.sub.2 CH.sub.3 PA1 R.sub.3 =CH.sub.2 OH, CH.sub.2 CH.sub.2 OH;
Furthermore, the present inventors have observed that in formulations containing grease-removal assisting magnesium compounds, the addition of minor amounts of builder salts, such as alkali metal polyphosphates, alkali metal carbonates, nitrilotriacetic acid salts, and so on, tends to make it more difficult to form stable microemulsion systems as well as causing residual deposits on the surface being cleaned, if they are incorporated into a light duty liquid detergent compositions.
U.S. Pat. No. 5,082,584 discloses a microemulsion composition having an anionic surfactant, a cosurfactant, nonionic surfactant, perfume and water; however, these compositions do not possess the grease release effect.
A major problem in cleaning of hard surface is the build up of grease on the hard surface. It is desirably in the cleaning of hard surface to be able to minimize this grease build up. The unique and novel microemulsion, all purpose hard surface cleaners and light duty liquid detergent compositions of the instant invention have incorporated therein a grease release agent which helps minimize the build up of grease on the surface being cleaned.